The invention relates to a method and device for assuring a fit to size assembly of components and machine parts in a structural unit or a machine, wherein fixed or relatively movable machine parts are sealed against inlet and outlet of fluid substances.
For a fit to size assembly of components and machine parts into a structural unit or a machine with sealing of clearances between fixed or relatively movable parts by means of a sealing member or a sealing system against inlet and outlet of fluid substances, the sealing member can have dimensions during the assembly which overpass the fitting dimensions for the assembly, thus hampering the fit to size assembly or making it impossible to achieve the functionally correct sealing position that cannot be adjusted later.
The functionally correct assembly of components and machine parts, e.g., in a machine having a rotary drive, e.g., in drives of transportation or mining machines requires that predetermined assembly steps be performed, with preliminarily mounted assemblies such as structural units, with the dimensionally accurate fit that do not allow for any dimensional deviations, especially an oversize, projection or overhang.
When sealing of these parts is absolutely required in assembling such machines or structural units, an elastic sealing member that is provided for sealing can be frequently displaced or even damaged, especially when an attempt is made to fit later.
It is an object of the invention to provide a method for a fit to size assembly of machine parts or structural components, wherein fixed or relatively movable parts, which are sealed against inlet and outlet of fluid materials, can be fitted without damage to a sealing system owing to their design.
According to the invention, this object is accomplished by the fact that an elastic sealing member is inserted, during the assembly of machine parts in a sealing relation, in an annular groove that is made in a machine part and communicated with a sealing seat and by the fact that, after the assembly of the machine parts, an overpressure is built up through a passage that is open to the outside in a space that is sealed by the sealing member inserted into the groove, whereby the sealing member is caused to move to the sealing position.
To carry out the method according to the invention, it is preferred that an elastic seal, generally an elastic rubber sealing ring used as the sealing member is stretched to a length that is greater than the length in the sealing position and inserted into an annular groove made in a machine part. The sealing member is thus installed in a position, which is not the sealing position, with an accurate fit with resect to the adjacent parts to form a correct assembly. The sealing member is moved from the fitting position to the functionally correct sealing position or to the sealing seat during the assembly through indirect or direct pressure application with a pressurized fluid in the direction of movement. For building up pressure, a fluid is used, e.g., a hydraulic fluid or a gas such as compressed air, or this operation can be carried out by using lubrication grease.
It is also preferred in carrying out this method that an auxiliary seal be installed in the groove that receives the sealing member. An overpressure in the space of the groove, which is sealed off by means of the auxiliary seal, acts in such a manner that the sealing member is caused to move to the sealing position under the action of the auxiliary seal moving through the groove under the effect of the overpressure.
It is also preferred that, in order to position the sealing member that has been moved into the sealing position, at least one positioning member, which is made of a non-elastic material, be provided between the sealing member and the auxiliary seal, which is used to assure a preset and stable distance between the sealing member and the auxiliary seal. In this case, the pressure space is sealed by the auxiliary seal, and there is no leakage of the pressurized fluid around it.
The method according to the invention can be used both for the static sealing where so called o-rings are normally used and for sealing rotating components where so called Turcan-Gly-Rings are generally used.